Manufacture of ether derivatives of carbohydrates like cellulose



ELLULOS E Bec, 2@ M33. A. w. SCHORGER MANUFACTURE OF ETHER' DERIVATIVES vOF CARBOHYDRATES LIKE C Filed Aug. v1.4. 1930 7 Pems of Efher Expos'zo/ fo I6 I6 zo 22 FROZE N 10o Paris of sO/vem 8% NaOH UNITED vSTATES PATENT OFFICE MANUFACTURE F ETHER DERIVATIVES, 0F CARBOHYDRATES LIKE CELLULOSE Arle W. Schorger, Madison, Wis., assignor to C. F. Burgess Laboratories, Inc., Madison, Wis., a corporationy of Delaware Application August 14, 1930. Serial No. 475,251

35 claims. (ci. 10s- 40) This invention relates to new carbohydrate Briey, the process consists in treating the carderivatives, especially cellulose derivatives, and bohydrate substance with caustic alkali solution methods for making them. It relates more parand subjectingthe resulting alkali carbohydrate ticularly to the hydroxy-alphyl ethers of celluyto direct contact with the etherifying agent, that lose and especially those hydroxy-alphyl ethers is, the olefne oxide, or a chlorhydrincorrespond- @1l in which substantially less than one hydroxyl ing to such oxide. These operations usually rehydrogen atom in -each cellulose unit is replaced sult in an impure form of the desired carboby an alphyl radical, and especially such comhydrate compound. In practice, optional subsepounds of this composition which are of limited quentoperations may be performed to purify the solubility in caustic soda solutions and are pracproduct and produce it in forms which are tech- 65 tically insoluble in caustic potash solutions. This nically more useful. invention relates also toan improved method for It has been known that carbohydrates Sueli eS making such derivatives whereby an olefne oxstarch and 0e11u10Se OOmbine directly With ethylide containing an ethylene oxide group react with ene oxide to form compounds which may be moist alkali carbohydrate and especially moist ethers, but which apparently are constituted 70 alkali cellulose. Some of the products possess somewhat differently than when mede by my physical properties and characteristics suitable method. The methods which have been used for for the production .of water-resistant, highly their preparation are such that the products have transparent films and laments,.plastic mxtures, little or no commercial value because of various insulating goods, finishing materials, etc. Other difficulties encountered in the process and their 75 forms are suitable for sizes, adhesives, filler for excessive cost. Furthermore, the products themadhesives, etc'. My new process permits of the selves are of such a nature that they apparently production of valuable intermediate forms of have 1itt1e practical application. For instance, if products as will be explained hereinafter. i one part of cotton linters is treated with 10 parts The raw materials Suitable for my product and ethyleneoxide at 100 C. for 10 hours a reaction process includev the following: carbohydrates piObably OCCI'II'S Since the 00tt0r1 linters Seem t0 such as cane sugar, starch, glucose, cellulose of gain Slightly iu Weight. but the resulting DIOduCt au'kinds, materials containing eeuulose, hydrated appears to be only a more reactive form of celluor hydrolyzed cellulose, raw or purified-viscose lose which is insoluble in a dilute caustic soda 39 (cellulose partially or completely xanthated) besolution. Onfthe other hand, .by my DIOCeSS, if 5 fore or after its spontaneous decomposition, other sufficient of the oxide reacts with alkali cellulose frecovered celluloses, and some derivatives of et'rOOm temperatures a peduet iS fermed iin-- cellulose, suchv as partially esterifled, alkylated, mediately, Which iS completely soluble in 10% or etherified cellulose, and suitable conversion CauStie Soda SelutiOIi; 01' in CaSe the eIuOuIlt 0f products of cellulose which are as little degraded ethylenev oxide is insuilicient s0 that a imeiI 90 or deplymerized as possible, amount of reaction product is insoluble inthe Myetherifying agent is essentially a compound Caustic Seda S01uti011, practically OOUlDlete apcontaining an ethylene oxide structure. It may parent solubility usually can be obtained by freezbe ethylene oxide as such or any of the oleflne iiig the reaetien DrOduCt With a dilute Caustic 40 h omomgs, such as prop'ylene oxide,buty1ene oir-. soda solution. Apparently the caustic alkali 95 ide amylene oxide or the higher homologs which serves as a catalyst in promoting the reaction be may b'e reactive oxides. Mixtures of these oxides tween the cellulose andolevne oxide. may be used. The chlorhydrins corresponding Although the ethers of this invention are deto these oxides may also be used in my process to scribed as being partially 801111010 in Caustic alkali make the derivativesv of my invention. Other solutions they form at least in. part so-called 100 ,chlorhydrins forming hydoxy-alphyl ethers as colloidal solutions therewith as they apparently enumerated in the'following specification also do not form true solutions. The ethers are dismay be used. persed by the caustic alkali, which is the peptiz'- It has been found that the higherthe number ing agent. Throughout the application and ct carbon atoms in the reactive etherifying comclaims when a solution of -the ether in caustic 105 pound the lmore diiilcult it is to effect the reac- Y alkali solutions is referred to, it indicatesda solution, that is, more heat and time are required, s c tion which may be partially or wholly colloidal. that the products and process are .practically I 'nave found that it is possible to produce a relimited to the compounds corresponding to the action between carbohydrates, for example, celhomologs at the lower end of the olene series. lulose, and ethylene oxide and/or some of its 110 homologs at room temperatures almost instantaneously, if the carbohydrate is rst treated with caustic alkali, presumably to form an alkali compound therewith. The ethylene oxide or homologous oxide, preferably in gaseous form, is then brought into contact with the resulting alkali compound, preferably at room temperatures. An exothermic reaction results which is vigorous, especially if the alkali compound is wet. By the term Wet I have reference to a material containing the amount of liquid which remains after squeezing, wringing, or centrifuging out the excess liquid resulting from soaking the material in water or a water solution of a chemical such as caustic soda. No excess of oxide is needed as the reaction is practically quantitative. If insufcient oxide is added so that some of the reaction product remains insoluble .in an aqueous caustic soda solution at room temperature it is necessary only to freeze the product in the caustic solution to obtain practically complete apparent solubility. Products made by reacting alkali cellulose vwith such oxides in proportions comparable to'those heretofore made by direct union of the oxide and cellulose have different properties indicating that specific methods of manufacture may determine specific properties in the product to meet the various uses to which the product maybe put.

Although hydroxy-alphyl ethers of cellulose similar to those which I have discovered have been known and described,` those ethers have contained at least one hydroxy-alphyl radical per cellulose unit. Those ethers were not of limited solubility in aqueous caustic alkali solutions..

Such prior hydroxy-ethers of cellulose have been produced by the action of ehlorhydrins such as ethylene chlorhydrin, propylene chlorhydrin and glycerol chlorhydrins on alkali cellulose with subsequent purification operations if a pure product was desired. I have found that with my improved method, I can use these same chlorhydrins to produce alphyl-hydroxy ethers of cellulose containing substantially less than one replaced hytion operations as had been previously found necessary. My improved method of reacting the alkali cellulose with the olefine oxide, especially ethylene and propylene oxides, to produce both the hydroxy-alphyl ethers of cellulose containing less than one replaced hydroxyl hydrogen. atom and those containing more than one replaced hydroxyl hydrogen atom per cellulose milt, has

advantages over the chlorhydrin method.

When making cellulose compounds embodying this. invention, the original cellulose material, as

hereinbefore described, may be used in the dry, air dry. moist or wet condition. It is rst mercerized by steeping it for a suitable length of time, such as from one to t'en minutes at room temperature or slightly above, in a caustic alkali solution such as a caustic sodasolution, which may rangev alkali solution. The caustic soda. solution itself absorbs small amounts of etherifying agent. It has been found that a 30% caustic soda solution absorbs less ethylene oxide and homologous oxides than weaker caustic soda solutions, whereas caustic. soda solutions stronger than 30% leave an excess of caustic soda. in the product which may be wasted in the subsequent operation. For example, I may use approximately 15 parts by weight of caustic soda solution to one part of cellulose. 'The mixture may be gently agitated to insure uniform mercerization. As the caustic soda in the solution present increases above 50%, the subsequent etherifying action is slglwer. Not

- only does the increased quantity of caustic soda present appear to slow down the reaction, but also an excessive amount of water has the same apparent effect. Therefore, I prefer to limit the Water present, yet to provide a caustic soda solution which does not contain more than 50% of alkali, and in consequence, employ an' alkali cellulose for etherication which is merely wet with a solution of the desired strength and preferably of 30% strength.

After mercerization' is complete. the excess caustic soda solution is eliminated by pressure. centrifugal action, or any other suitable method until the cellulose content of the mixture has increased to at least 20%, and preferably to between 25% and 35%. I prefer to callthe resulting material a wet alkali cellulose. The etherifying agent is then brought into intimate contact with the wet alkali cellulose and the proportion of the reacting constituents is carefully regulated. Although any of the etherifying agents and cellulosic materials heretofore mentioned may be used, for purposes of illustration I rst will describe in detail a process employing ethylene oxide and cotton linters or some other form of high grade alpha cellulose, and one in which refrigeration is not necessary. Those skilled in the art may readily adapt the following procedure to other cellulosic materials. Degradation of the cellulose through excessive ageing of the alkali cellulose tends to make the Aetherifed product water soluble and therefore must be avoided Where water insoluble products are desired. Throughout the specification, when cellulose or alkali cellulose is referred to, it is understood that the cellulose has not been degraded sufficiently, unless such degradation is mentioned specifically, to increase the solubility of the resulting ether beyond the limits set for such solubility in caustic alkali solution.

.Under ordinary conditions of room temperature (20 C.) and atmospheric pressure, ethylene oxide (boiling at about 10.7 C.) is a vapor. It is usually. stored and shipped under pressure in metal cylinders. It may be conducted as a vapor directly from such cylinders to a suitable gas tight reaction chamber containing alkali cellulose, the rate of flow being regulated in consideration of the rate of absorption by the alkali cellulose. To regulate the quantityV of ethylene oxide used the cylinder may be supported upon weighing apparatus suitablefor 'indicating its decrease in weight. The ethylene oxide vapor also may be conducted directly to the alkali cellulose .from an oxide generating chamber or it chamber if desirable. Evacuation of .the reaction chamber prior to the introduction of the 'oxide is desirable since it hastens the reaction and results in a' more uniform etherification. Ethylene oxide is introduced into the reaction chamber at may be generated in the alkali cellulose reaction .1

a rate somewhat in excess of the rate of absorption and after a suicient quantity has been introduced, the now is stopped. The mixture is agitated during all this time and agitation is continued until absorption to the extent desired is practically complete.

The etherifying reaction is exothermic and cooling may be necessary to prevent charring of the cellulose. I prefer to maintain the temperature of Athe reacting mixture below C. The agitation of the mixture also prevents localoverheating. It is not necessary, however, to keep the temperature below the 45 C. specified since it only is necessary lto avoid charring, which does not take place until a considerably higher temperature (about C.) is reached. Stirring also ensures that the ethylene loxide will reach all of the alkali cellulose. The etherifying operation may be continued until the supplied quantity of ethylene oxide is absorbed. Where it is not desirable to refrigerate the resulting Aether to secure practically complete solubility in dilute caustic soda solutions it is necessary to react about 11% to 20% or more of ethylene oxide (based on the cellulose-in the alkali cellulose) with the alkali cellulose. If the refrigeration isv practiced freezing in the presence of the caustic soda solution. It is possible that some of the cellulose units may absorb more or less than the calculated amount of oxide. Furthermore, the ethylene oxide may form a limited amount of ethylene glycol or diethylene oxide. These facts may account for a measured absorption in excess of theoretical predictions. When more than the preferred amount is used there may be waste and the quality lof the product is injured for certain purposes as will be explained hereinafter. The properties of the' product vary with the amount of ethylene oxide absorbed whiqi may be as high as 200%.

. It is believed that under the above reaction conditions the union of the cellulose and ethylene oxide is effected by the substitution of the ethylene oxideradical for the hydrogen atomof hydroxyl groups (preferably primary) of a cellulose unit or of two or more linked cellulose units. whereby one valence of the oxygen atom of the oxide is replaced by an Ahydroxyl hydrogen atom of the cellulose molecule to form an hydroxyl group attached to the ethylene radical. It is believed that the reaction for the dicellulose ether 130 takes place as follows:

Cellulose the larger amount of ethylene oxide may b e reduced. A high grade cellulose such as cotton linters requires a larger amoun of ethylene oxide to secure complete solubility than a highly purified cellulose made from wood pulp, the latter apparently being less resistant chemically.

The product obtained by the processoutlined hereinabove probably is an impure ether of cellulose and ethylene oxide having a glycol structure, one. impurity being the caustic alkali which, although present-to ensure success of the process, probably does not enter into the reaction directly and, after the reaction is complete, remains as an impurity. Where ylene oxidebased on the cellulose content is supplied and absorbed itis probable that two uni-ts `the formula below is 13.6% tent. When less than 15% of ethylene oxide is 4made from cotton of cellulose are combined with each molecule of ethylene oxide; hence rthe probable appropriate chemical designation is ethyleneglycol(di)cellu lose or dicellulosehydroxyethyl ether. A unit of cellulose is here defined as CsHioOs.

Theoretically the ethyiene oxide content o: the dicellulosehydroxyethyl ether' as represented4 by of the cellulose conbetween the alkali cellulose linters or other form of used the reaction high-grade alpha cellulose and that only a small amount of 'residue insoluble ina dilute caustic ,soda solution remains. Under the most carefully controlled conditions I have made a compound with 11% to 12% 'conditions of reactiony it is necessary Ato. supply about 18%I to 20% of ethylene oxide for com-v plete solubility v(using a high-grade cellulose) in 'dilute caustic soda solution, provided the reaction j; product is not subjected to a temperature belowrv about 14% to 15% of eththe ethylene ox-Jb ide at about 0 C. must be carefully controlled sothe reaction onl a pri- More generically ex- The foregoing illustrates mary hydroxyl group.

pressed, the reaction is undoubtedly .ferent products are formed or a mixture of two different products are formed. In the refrigeration method to be hereinafter more fully described. it is probable that one ethylene oxide molecule or hydroxy-alphyl, radical combines with aggregates consisting of four cellulose units. The aggregate suffers oxide or alphyl radical is added.

` If acidied and then washed free of the resulting salts and remaining acids after such operations as have been described, the products retain the physical form and megascopic structure of :l the material from which it is derived, that is, in this case, the'fibrous structure of cotton linters or other alpha cellulose. After Washing, it may 'be dried and shipped in such fibrous form or it lit .sulphate slightly acidied with sulphuric acid.

The ethers of my'invention differ from the ethers made previously and described in the literature and patents with respect to their solubility in lcaustic alkalies. My ethers made by absorption 'f less degradation whenl less 13|) -A .solutions.

` in caustic soda solutions containing less than in the weaker caustic soda solutions.

' inthe range between 15% and 20%.

from 2% to 6% of caustic soda, the ethers higher in ethylene oxide content being more soluble The reverse is true when the caustic soda solutions are The greatest solubility seems to be in to 15% solutions of caustic soda with the maximum at about These same ethers containing up to about of added ethylene oxide are but partially soluble in caustic potash solutions of any strength. Of these others, those containing from 13 to 14% to about 20% of added oxide, though only par-A tially soluble, show the largest solubility of any of my ethers in caustic potash solutions of about 15% to 20% concentration, although most of -them are less than soluble. The ether solubility or dispersion in a caustic alkali solution apparently increases more or less directly with the concentration of the etherifying agent. However, the solubility or dispersion of the ether may vary over a Wide range in a small range of caustic alkali concentration as is shown in the accompanying solubility curves. At about an 8% ether concentration the clear solution is highly viscous so that solutions of much above that concentration are of little interest.

The solubilities given above and as defined for the claims are based on measurements made at room temperatures and on both dry and moist ethers made from alkali celluloses in which the cellulose has not been `subjected to the action of causticalkalies for an excessive length of time,

Y thatis, the cellulose has not suffered enough degvThesolids thrown out of solution are washed by further centrifuging, thrown into a coagulating bath (alcohol-acetic acid mixture) ltered, dried, and weighed. That portion of the ether which is thrown out of solution since it is not sufficiently dispersed to form a clear (to theeye) colloidal suspension or solution is regarded as not soluble since such undissolved ether cannot be tolerated commercially where clear solutions are required.

For special purposes a greater degree of disper-` sion-may be required. The ether apparently diserses to varying particle sizes according to its concentration in the caustic alkali solutions. It disperses to a finer state of division, therefore indicating a higher solubility, the lower its ratio to the solution. The greater the dispersion'the smaller the amount of ether which is thrown out by centrifuging and the higher the apparent solubility. I have accordingly used a low ether concentration when determining the solubility thereof sin'ce solutions of such low concentrations are below those of any commercial importance,

and,.furthermore, a limited solubility of the ether in such concentrations indicates a much lower solubility in those concentrations of commercial importance. The solutions of low ether concentration are also less viscous and more amenable to the necessary manipulations.

The ethers should be substantially soluble in dilute caustic soda solutions if they are to be used directly and are to be of any commercial importance where transparency and freedom from insolubles is required. Practically all commercial solutions are viscous and 5% of insoluble ether in such a viscous solution prevents it from being filtered to remove any considerable amount of insoluble matter or otherwise manipulated electively. For instance, if the ether is not suiciently soluble in caustic alkali solutions, a film made therefrom is not clear and transparent, or if the soluble portion is filtered off after diluting the solution suicently to make it Iiltrable, it does not form a usable film because of the low ether concentration. Such low concentration solutions also cannot be used for making imitation silk fibers. A film made for commercial purposes 'should have a thickness of about .001 inch when dry. A solution 'containing at least 5% of the ether is usually required to make a satisfactory film. The solution should be practically clear to the eye though it may even then contain insufflciently dispersed cellulose compounds which may prevent the making of a high grade product. The solubility of the ether in caustic alkali solutions may be increased by freezing it in the presence of caustic alka-lies provided that the ether is subjected to the action of the solvent caustic alkali directly after freezing, that is, the ether is not precipitated o ut of the alkali after the freezing operation. The freezing operation disperses the ether more effectively and clear solutions are obtained more easily.

Whenever dilute caustic alkali solutions are mentioned in this specification they relate specifically to solutions containing from 2% to 25% of caustic alkali and sometimes may refer to solutions containing from 5% to 151% caustic alkali, especially in connection with'caustic soda solutions.

Not only is the product containing a lower amount of ethylene oxide less soluble in dilute caustic alkali solutions but it is also cheaper to make because of the relatively high cost of the etherifying agent. It also has superior properties for many purposes. As hereinbefore described, the product formed by the absorption of less than about 1lr% to 15% of ethylene oxide may be made more soluble or entirely soluble by a.

suitable freezing operation. It is practically impossible to filter this insoluble product (usually gelatinous fibers) from -the viscous solutions of the ether in caustic soda which are required in the arts, and therefore other methods must be used.

In the accompanying drawing:

Fig. 1 illustrates the apparent (solubility of a series of ethers in caustic soda solutions;

Fig. 2 illustrates the increasedV solubilities over those in Fig. 1 produced vby the freezing process of this invention;

Fig. 3 illustrates the apparent-solubilities o1* a. .series of ethers in .caustic potash solutions;

. Fig. 4 illustrates specifically the eiect of freezing toA increase solubility.

I do not intend to bind myself closely to the properties of the ethers as indicated by the curves Iin the figures, since the properties are variable and are determined by the various factors herein described. The curves are given only to illustrate properties graphically for visualizing the numerous general statements herein made, and to permit one to recognize the direction in which the properties change with changes in the process.

The data for curves which appear in full lines have been rather quantitatively found to locate the' same on the chart. The dotted line curves are'predicated on many qualitative observations, and considerable experience within covered, and represent generally what I believe to exist. I y

In Fig. 1., the curves are ardized test, by subjecting two parts by weLght of an ether containing various amounts of ethylene oxide to solution in 100 parts by weight of various strengths of caustic soda. The percent o f the exposed ether which is dissolved or dispersed in the caustic soda is plotted vertically against the strength of the caustic soda solution. Curve 10 corresponds to the tetra-cellulose ether, containing about 6.8% ethylene oxide. Curve 11 corresponds to a dicellulose ether containing about 13.6% ethylene oxide. Curve 12 corresponds to a mono-cellulose ether containing 27.2% ethylene oxide. Curve 13 corresponds to a more complex ether containing 40.4% ethylene derived, asvby a standy oxide.

Fig. 2 is derived in the same way as the curves in Fig. l1, but the product was frozen, as elseincrease the solubility. Curves 14, 15and l'correspond respectively to the materials of curves 10, 11 and 12 of Fig. 1. The two figures show the increase in solubility which is most notable in the more dilute caustic soda solutions. l

Fig. SArelates to caustic potash solutions and indicates the lessened solubility therein. Curve 17 represents a dicellulose ether without freezing, and curve 18 indicates the increase over 17 by freezing the product. Likewise, curves 19 and 20 indicate respectively the relative solubilities of a mono-cellulose ether, unfrozen and frozen.

In'Fig. 4 two curves are shown based upon the following-table of data:

Solubility of an ether containing 8% ethylene oxide in caustic alkali solutions ether which is insoluble The ether` was practically entirely insoluble at room temperature in 8% KOH.

Curve 21 represents the amount of undissolved etherat the various concentrations when solution is eifected without freezing. When the same the ranges `potash therefore obviates 7ture. v A similar mixture when solution uble portion is substantially al1 rendered soluble over the range indicated. The curve 22 represents the small amounts found undissolved after freezing. The shaded area 23 therefore represents graphically the advantage of the freezing process. f r

The low partial solubility of my ethers in caustic potash solutions is also of further technical importance. If cellulose is mercerizedwith caustic potash and then etheriiied the resulting ether may be washed directly with water to remove the caustic potash contained therein since the ether is 'practically insoluble in most caustic potash solutions. This is not possible with the ether made from soda cellulose. The use of the caustic t the necessity of neutralizing the caustic alkali in the ether with an acid which makes it impossible to recover the alkali. On the other hand the caustic potash solution washed from the ether may be evaporated to mercerizing strength and again used. Last traces of caustic potash in the ether may be neutralized by means of an acid.

I have found that if the alkali cellulose, mercerized as previously described and then subjected to ethylene oxide or homologous oxides at temperatures below charring and preferably at or about room temperatures, in an amount which does not give a product completelysoluble in caustic' s oda solution, is then refrigerated until the caustic soda solution freezes, the product becomes more soluble or completely apparently soluble. The insoluble fibers have been so modified by the etheriiication process that they require only is frozen, as herein described, the insol' the change, perhaps only a mechanical disinuble in dilute caustic soda solutions (5% to 15%) although containing only about 7% to 8% of ethylene oxide based on the weight of cellulose used. As an example, an ether containing 8% ethylene oxide, when subjected to the action of 121/2 times its weight of 8% caustic soda showed 34.1% insoluble in v24 hours at room temperasubjected t0 a temperature of -20 C. for the same length of time showed but 1.20% insoluble. This indicates that one ethylene oxide unit combines with four units of cellulose to form ethyleneglycol (tetra) cellulose or tetracellulosehydroxyethyl ether in which compound the oxide is in the proportion ofv6.8% of the cellulose content.A With less thannthis amount of oxide a more or less cloudy solution is formed, even when the etherv is dispersed by freezing, showing ,that a portion r of the cellulose ether compound or reaction product is insoluble. I have, however, made reaction products containing as low as 3.5% added ethylene oxide which, with'freezing'are largely soluble in a 10% caustic soda solution. Such solutions containing undissolved cellulosic mate' Y rials in suspension may be technically useful and As another are within the scope of my invention.

to 14%- of example,- an ether containing '12% added ethylene `oxide may appear L completely soluble to the eye but \contains dispersed particles sufficiently large to prevent making a product of the highest degree of transparency. A freezing operation will -further disperse these particles'to produce arsolutionI which yields iilms of the highest transparency.

The compound formed which contains less than` 13.6% of added oxide necessary for the ethyleneglycol (di) cellulose ether and especially the compound containing less than 10% of added oxide or more than about 3 units of cellulose has many desirable properties. The cellulose compound of ethylene oxide of these proportions which, when thrown out of solution when the alkali solution reacts with an acid or other precipitating agent, is tougher and stronger than one which contains a higher percentage of oxide. It gives a lm which is flexible and may be stretched without the addition of glycerine. The superior physical properties of the product indicate that the cellulose has'unde'rgone little degradation. It furthermore makes possible the use of various chemical wood pulps for the manufacture of high grade films land filaments now only possible when made with specially prepared wood pulp or cotton linters.

Films and filaments and the like may be made from the hereinbefore described ethers containing an ethylene oxide content up to 20%. If the added ethylene oxide is in excess of approximately- 20% of the weight of cellulose in the alkali cellulose thelms and filaments become softer and slimier when wet. The greater the excess of oxide the more pronounced these characteristics become. Furthermore, with increased alphyl content the product tends to become more soluble or entirely soluble in caustic potash solutions, very dilute caustic alkalies and water. This ordinarily is not desirable. I therefore prefer making a compoundl that consists of substantially less than about one molecu-v 'f lar weight of ethylene oxidev to one unit of cellulose, and containing usually less than v20% of added ethylene oxide. This applies also to the compound whether made with ethylene oxide or ethylene chlorhydrin. ,tu When making lms and laments and the like the ether is dissolved in a caustic soda solution, a weak caustic soda solution of about 21/2% to 3% strength being used for an ether of about .20% added ethylene oxide content and about 5% caustic soda for one which has had to be frozen in order to make all of the ether soluble. Suicient caustic soda solution may be used to produce a solution containing any desired amount of cellulose ether, the ether concentration usually being from 6% to 8% or 9%.

The solution is usually clear, but as a precaution may be filtered to remove whatever dirt or other solids, or undissolved matter that may be present. Its viscosity may be made such that it is capable of being extruded from dies into a number of forms, such as lms or filaments, continuous tubing, or made into bottle caps, insulating goods, and the like. It may be extruded into' a coagulating bath similar to that employed in the manufacture of lms, filaments, and the like from viscose, namely, of the approximate composition: sulphuric acid, 20% sodium sulphate and the usual organic compounds such as glucose, and inorganic salts such as zinc sulphate, magnesium sulphate, etc. The product sets into a transparent, non-fibrous, solid substance which,

after washingv in water has a good wet and dryr strength. Threads and sheets made from the new product possess good physical properties. L, The films or filaments so made are clear and uniform in color, often do not require bleaching, are hard and rm in texture, and possess good tensile strength.

Following is an example in which refrigeration is used. The cotton linters or chemical wood pulp are mercerized in the usual manner as hereinbefore described. The excess caustic alkali is removed as described. The alkali cellulose is exposed to the desired amount of ethylene oxidesay not more than 6.8% to 10 %-until the oxide is absorbed. Water is added to this product until the strength of the caustic soda solution (the cellulose ether not included) is reduced to 2% to 10%', preferably 4% to 6%, the optimum being about 4.75%. Caustic soda solutions of 2% to 10% strength start freezing at from -0.3 C. to -10 C. If sodium chloride or other salts are present in the caustic soda solution the percentage varies accordingly from those given. The mixture is refrigerated to such a temperature that a mass of crystals of ice forms and preferably until the caustic soda solution freezes. Although the water starts freezing and ice separates from a solution containing less than 20% caustic soda, the residual caustic soda solution itself does not freeze until a concentration of 20% is reached. A 20% caustic soda solution freezes at 20 C. This temperature is the most effective. Lower temperatures may be. used. Long exposure to these low temperatures is not harmful to the product. The frozen mixture has a cheesy consstency and contains ice crystals and hydrated caustic soda crystals if the temperature is maintained at 20 C. or lower. The mass is allowed to melt and come to room temperature. If necessary more caustic soda is added, and preferably to the melting mass to prevent gelling at room temperature, since the ether containing '7%- ethylene oxide requires at least a 6% caustic soda solution to produce complete solubility. The higher ethers permit the'use of weaker caustic soda solutions. The compound ofcellulosev and ethylene oxide or homologous oxides on melting is transformed into a syrupy solution in the caustic soda. This solution, when made under the optimum conditions, is practically free from insoluble cellulosic materials and may be treated y in much the same manner and used for many of the same purposes as the product obtained when 13% to 20% of the ethylene oxide is present in the compound.

.Its superiority for certain purposes has been discussed previously. Although a specific procedure `has been given the amount of ethylene oxide and the refrigerating temperatures may be I varied overJ a wide range to secure specific products without departing from the scope of my invention. Refrigeration sometimes may be used to advantage for products containing a high percentage of oxide if a small amount of insoluble cellulosic material remains after dissolving the reaction product ina caustic soda solution.

v In the above example in which refrigeration is used the cellulose is m'ercerized with a- 25% to 30% caustic soda solution, and then squeezed to remove excess caustic solution. After etherication when Water is added to decrease the caustic soda concentration to about 4.75% for the freezing. operation, the ether concentration'in the final solution is too lo'w (about 5% to 6%) for 4.75%-, It may have a concentration of from 7% to 9% of the ether derivative. yIt is then frozen, after which it is thawed .with proper caustic soda addition. Thisproduces an ether concentration of 8% to 8.50% which is desirable for many purposes. If desired the entire reaction product may be first acidfied, washed, and then frozen in caustic soda solution.

Although caustic soda is the specific caustic alkali specified during the refrigerating operation it is possible to use caustic potash solutions though the concentration limits are narrower.4 It is possible by the refrigeration method to increase somewhat the very limited solubility in dilute caustic potash solutions (10% to 25%) of the ethers containing a low percentage of hydroxyethyl radical. These ethers which show an increase in their very limited solubility in dilute caustic potash solutions after freezing, do Anot retain this increase in solubility after being again precipitated from causticalkali solution, unless subjected to refrigeration again. These results are similar to those obtained when caustic soda solutions are used.

It is also possible to remove small amounts of insoluble reaction product from hydroxy-ethers containing a low percentage of hydroxy-alphyl radical by dissolving the etherified reaction product in a dilute caustic sodasolution (about 6% to 10%) and iiltering off the small amount of insoluble matter. The ether concentration, however, must be low to filter the solution. As this procedure results in a solution of ether too dilute for most purposes it is necessary to evaporate off the excess water or to precipitate the ether from it. After precipitation and washing it is redis-- solved to the desired concentration in caustic soda solution. *Refrigeration may be used to aid solution. This method has too many disadvantages for practical purposes and also tends to degrade the cellulose, thereby increasing the solubility of the nal ether in caustic alkalies.

It is possible also to react the ethylene oxide with cellulose directly with or without a catalyst as has been previously known in the art, and

'then refrigerate these products vwith caustic soda solutions, thereby rendering soluble, or increasing the solubility of, those compounds of ethylene oxide and cellulose which have been regarded as insoluble in caustic soda. I have treated wood pulp with 12% of ethylene oxide, using a temperature of C. and pressure, in the absence of alkali, producing a product insoluble in dilute caustic soda solutions at room temperatures. The entire reaction product was then frozen in a dilute caustic soda solution and on melting the solubility of the product in dilute caustic soda solution seems to have increased, judging by the increase inthe amount of gel-like material.

I am able by my improved process to make those compounds which are lowest in cost and most useful in the arts and which apparently were not' produced vby the processes heretofore known. Those compounds which were not previously produced and which are most valuable are those which are insoluble in water and practically or almost insoluble in dilute caustic potash solutions, and which have bility in dilute' caustic soda solutions as hereinbefore described, and which contain substantially less than one molecular weight of olene oxide in combination with 'one unit of cellulose (CsHioOs), and especially lthose containing less than one molecular weight of oxide to two units of cellulose.

a limited partial solu- Although hydi.,xy.alphyl ethers of cellulose have been made by reacting upon wet alkali cellulose 'with a halohydrin of a polyalcohol the ethers resulting from that reaction have been described as being easily soluble in aqueous caustic alkalies and as being derivatives in which at least one hydroxyl hydrogen atom of the cellulose is replaced by an hydroxy-alphyl group. The relatively large amount of ether-forming compound thus introduced into the cellulose molecule by the above method apparently resulted in the production of derivatives which showed a high solubility in the caustic alkalies. Such compounds are of little commercial importance. I have found that it is not necessary to use the halohydrin since I apparently can produce the same compounds by utiliz'ng the gaseous oxides which result when the halohydrin reacts with caustic alkali. I also have found that it is possible to apply the refrigeration principle to the cellulose halohydrin.

Oleine chlorhydrins, such as propylene and ethylene chlorhydrins, and glycerol monochlorhydrin, also known as alpha monochlorhydrin, may be used to produce the hydroxy-alphyl ethers. The glycerol oxide corresponding to the glycerol monochlorhydrin is very difficult to make and therefore is not at present of importance for the commercial propyl ether of cellulose. If hydroxy-ethers are to be produced which have substantially less than one hydroxy-alphyl radical per cellulose unit I have found that it is drins in practically dehydrated condition. It is also better to use a stronger caustic alkali solution for mercerizing the cellulose. Instead of using Athe 30% solution which I prefer with the ethylene oxide method I prefer using about a 40% caustic soda solution. If the commercial ethylene chlorhydrin, which contains about 60 water, is used, the results are unsatisfactory and the reaction is incomplete. A large amount of .cellulose apparently remains unacted-or only slightly acted upon oxide, contain a certain amountrof cellulose reproductionv of the dihydroxy- 'f' better to use these chlorhy-V lil) LLC;

action products which are insoluble in a dilute caustic soda solution and it becomes necessary to freeze the solution as previously described to make these insoluble products more soluble. The sode cellulose after being treated with the chlorhydrin contains not only the hydroxy-ether and the insoluble particles of cellulose compound but also'the sodium chloride .which is formed by the chlorine in the chlorhydrin. This mixture may be Dfrozen directly without the removal sodium chloride or the mxture may be neutralized, washed to remove the sodium chloride, and then frozen. These procedureswll be further i1- lustrated in specific examples. Y

Using cotton linters as a base the product when dissolved in dilute caustic alkalies often becomes excessive for ordinary purposes. v I nd that this viscosity can be reduced and the tendency tolsolubility in water of the the viscosity of l increased to any desired extent without changing A the resulting alkaline solution of the ether.

Higher temperatures in ageing produce a lower viscosity, and increase the solubility. Excessive lowering of viscosity may result in derivatives that produce'weak films or filaments. Higher temperatures in the etherifcation do not ap- 'preciably increase solubility. Thereseems to be no direct relation between viscosity and solubility, but depolymerization of the cellulose both lowers viscosity and increases solubility. Higher proportions of oxide lower viscosity and increase solubility.

As mentioned heretofore, I may use cellulosic material other than cotton linters. Cotton linters are probably the least depolymerized form of cellulose obtainable. If amore depolymerized form such as chemical wood pulp is used, thev other obtained is made water soluble more easily, the solubility increasing with the extent of depolymerization of the raw cellulosic material. However, even depolymerized celluloses such as artificial silks, consisting of cellulose regenerated from viscose solutions, form water insoluble products if treated with. moderate amounts of ethylene oxide in the presence of caustic alkali. Such cellulose (without mercerizing) forms water soluble products with ethylene oxide directly if heated with an excess of oxide at '100 C. for a number of hours, Whereas the same treatment with cotton linters or wood pulps results in a product which cannot be distinguished from the original cellulose except that it is only slightly more reactive (e. g. to esterication) but it is not soluble in water,'caustic soda, or organic reagents at ordinary temperatures. The etherifying action which occurs when the oxide reacts with the alkali cellulose thereforemust be different than when the oxide reacts directly on the cellulose. There are many practical industrial applications for a water soluble product, in a dry fibrous form or in aqueous solution. Some of the uses to which it is applicable are: size for textiles, adhesives, ller for adhesives, base for explosives, etc.

The formation of awater soluble product from alkali cellulosedepends on the kind of cellulose (wood cellulose, hydrocellulose, etc.) and the ageing of the alkali cellulose, or ether solution, etc.

as previously explained. The process for prof ducing the soluble product from ordinary pulp is simple. The raw cellulosic material such as chemical wood pulp is mercerized to obtain alkali cellulose, allowed to stand for 24 hours in limited contact with air, and etheried with a large amount to 90%4 or more) of ethylene oxide as above described. The oxygen of the air oxidizes the cellulose and renders it. more easily dispersible. In permitting contact with air the material is best maintained in a loose fluffy condition in a container having a loosely fitting cover through which air may enter. Further standing in Contact with excess alkali may be necessary. To form the dry; brous product, the impure ether is neutralized with a suitable acid, Washed with alcohol, and dried. To form the aqueous solution the impure ether is dissolved in water or 5 caustic' alkali solution. It then may be neutral- .organic solvent such as alcohol, or may be removed by dialysis or byV drying the neutral product andleaching the salts therefrom with a nonaqueous solvent. After the salts are removed, the

material may be dissolved in water and the viscosity of the solution may be regulated to any desired value.

Such material is valuable as an adhesive,A either alone or with sodium silicate,

and may also be used as a filler for inks or other scraps in a caustic alkali solution and using it for any desired purpose for which a fresh solution may be used. Furthermore no odors nor poisonous gas are liberated by the coagulating bath. Viscose must .always be fashioned into its final form after a period. of carefully controlled ageing whereas my ether, once purified and freed from caustic soda, may be stored indefinitely in the diy state, or in water if a mold preventive, such as formaldehyde, is present. It may be used at any time. In the presence of dilute caustic soda solution, the solution shows relatively little change with age as compared tosimilar viscose solutions. Of course, either product may be stored safely if refrigerated. Furthermore, the sodium cellulose xanthate, of which viscose is comprised. is unstable and is subject to spontaneous decomposition. whereas my product is relatively stable and suffers only a slight drop in viscosity while ageing in dilute caustic soda solutions. A

' further advantage of my product lies in the ease and simplicity with which the washing of the coagulated product is accomplished. Washing in water is all that is required, whereas in the case of viscose, the large quantities of sulphur in the impure coagulated product must be eliminated and a number of washing and bleaching operation's must be performed.

The ethylene oxide or other olefine hydrocarbon oxide may be dissolved in benzol or some other non-reactive organic solvent 'and this solution used to react with the alkali carbohydrate. specific illustration is given hereinafter as Example V.

Although I prefer to use the etherifying agent in the vapor phase, I may use it in its liquid phase aswell as in a solution. Example VI given hereinafter illustrates the use of an oxide in its liquid form.

The compounds of cellulose and propylene oxide, butylene oxide, and amylene oxide, may be prepared in a manner similar to the method used for the preparation of the ethylene oxide compound with due regard to the slight differences in the physical and chemical properties of these oxides. The slight differences in manipulation necessary will be understood by those skilled in the art. The resulting compounds have tho'se differences ln their properties as are to be expected in 'a series of such compounds. If propylene oxide is used asthe etherifying agent, the following example shows how it may be used without freez-v ing. The carbohydrate such as cellulose is treated with alkali by steeping ,and then removing the excess as hereinbefore described for etherication by ethylene oxide. The resulting alkali cellulose is then treated with a measured amount of propylene oxide (boiling point 35 C.) in a.v

closed container at about 35 C. to 40 C. In a specific instance when 12.6% of propylene oxide was absorbed, the reaction product as a 6% solution vof ether in dilute caustic soda, resulted ina translucent syrup containing many undissolved bers; at 17.6% there was increased solubility but many. undissolved fibers; at 22.4% most of the fibers were soluble in a`caustic soda solu- .formed by the mixed oxides and sometimes used to advantage to replace the separate compounds.

When using chemical wood pulp instead of cotton linters to produce ethyleneglycol(di)cel'- lulose ether or the other compounds containing a higher proportion of the etherifying reagent, I prefer to steep the sheets of pulp in about 15 parts of 18% to 25% caustic soda solution, and

- then squeeze to form an alkali cellulose containing from to 35% cellulose. This alkali cellulose is then etherif'led in a closed container with ethylene oxide at room temperature. If ethyleneglycol(di)cellulose ether is desired about 14% of the oxide based on the cellulose content is used. The balance of the procedure is the same as` before. Filmsand filaments made from the wood pulp compound are weaker when wet than a similar compound made from cotton linters.

If compounds of the carbohydrates not of a.

cellulosic nature are to be formed, the procedure which is followed is similar to that used with cellulose, giving due regard to the differences in the chemical and physical properties of these compounds. Such carbohydrates may be starches, sugars, such as cane sugar, glucose,

etc., and include such carbohydrate derivatives as contain hydroxyl groups that are reactive with .ethylene oxide. These materials after treating with alkali react with ethylene oxide and propylene oxide and other oxides of the olefine series with great vigor. The large amount of heat liberated readily produces a sufficient rise in temperature to cause charring if the reacting materials are not cooled. A large excess of lethylene oxide renders the product soluble in alcohol. Glucose and cane sugar and othersimilar carbohydrates may be etherified in a like manner to starch. Refrigeration may be used with the starch as with cellulose but there does not appear to be any advantage gained because all of the products are Water soluble, including the alkali starch.

vThroughout the specification etherication has been used to denote the reaction in the presence of alkali between the carbohydrate and the -reacting oxide, or chlorhydrin. The product resulting from the addition of suitable alkali to the various carbohydrates is called alkali carbohydrate and in the vcase lof cellulose alkali cellulose". The final product also has been called an ether although 'the definite structure of the product is not known.

It is probable that the cellulose'ethers made according to my invention are hydroxy-alphyl ethers of cellulose. Those ethers madeby reacting the alkali cellulose with ethylene oxide or ethylene chlorhydrin are probably hydroxy-ethyl ethers of cellulose, those made by reacting the alkali cellulose with propylene oxide or propylene chlorhydrin are hydroxy-propyl ethers of cellulose, those made by reacting alkali cellulose with glycerol monochlorhydrin are dihydroxypropyl cellulose ethers.

Throughout the specification I use the term alphyl as indicating a radical of the aliphatic series inasmuch as the term alkyl which is sometimes used to make this distinct reference is frequency indicative of bothaliphatic and aromatic radicals. The term alphy is specific to the aliphatic series in the same manner as ary lis specific to the aromatic series. See Richters Aluloses, and .substances related to them. These polysaccharides may contain two or more units of CsHmOs. The cellulose molecule which has not been depolymerized, may contain four such units and my experiments indicate that four or possibly more of such units will combine with one or more ethylene oxide molecules to form a compound soluble in dilute caustic soda s olution (5% to 15%). The carbohydrates like glucose, which, on the other hand, consist of one such unit, probably united in equi-molecular proportions with the oxide.

It is to be observed that in the process of carrying out the reactionsjof this invention it may be difficult to control the reaction so that every unit of carbohydrate is similarly combined with an oxide molecule. Some units of carbohydrate may be deficient in and others may be over-supplied with the oxide, while the average aggregate and the greater percentage of all the aggregates may be similarly combined. Therefore in the appended claims it is contemplated that the products claimed are not composed entirely, but 'only predominantly, as specified. Whenever the percentage of oleine oxide or alphyl radical is specified, it refers to the added amount rather than the actual amount. This is necessary because of the dificulties encountered in analyzing the reaction Aproducts to determine their exact constitution.

Whenever a reference is made to olene oxides containing an ethylene oxide group it is intended to cover those oxides in which the oxygen is linked to two adjacent carbon hydrogen groups thereby forming an ethylene oxide group -within the olefine. Whenever a non-substituted olefine oxide is referred to this does not cover the homologous oxides of the series. Propylene oxide may, for example, be called methyl ethylene oxide and may possibly be regarded as a substituted oxide but by me it is not so regarded.

The following specic examples of the invention are given by way of summarizing the invention in its various'modications. Other modclaims;

EXAMPLE I Cellulose-ethylene oxide water insoluble compound suitable fof:` films, filaments, etc., containing 20% ethylene omide based on original cellulose 100 parts by weight (dry weight) of cotton linters .are thoroughly stirred into 1500 parts by weight of 30% caustic soda solution. After stirring for several minutes to insure thorough wetting of the linters by the caustic soda solution, the linters, now changed into alkali cellulose, are passed through squeeze rolls to remove the excess caustic soda solution and to increase the cellulose content of the mixture to about 30%. The mixture after shredding is a wet, fluffy, fibrous mass. It usually is not allowed to age more than 24 hours at about 20 C. It is put into a tightly closed reaction chamber in which stirrers keep the alkali cellulose thoroughly agitated. Cooling means on the exterior of the reaction chamber may be necessary if the etherifying action is too violent. It is preferable to evacuate the reaction chamber prior to the introduction of the oxide as this hastens the reaction and allows the reaction to proceed more uniformly -throughout the alkali cellulose. While the alkali cellulose is being stirred Ivigorously about twenty parts of gaseous ethylene oxide are admitted at a rate which does not allow the reacting mass to go over a temperature of 100" C. For the best results the temperature is kept below 45 C. The resulting product is still fluffy and retains the physical megascopic form and structure of the linters. This product then may be processed in two ways:

(A) To neutralize the excess caustic soda, it may be treated with a ldilute acid, preferably hydrochloric or sulphuric of about 5% to 10% strength. If the fibrous compound is stirred into the acid vigorously,'local formation of gel spots may be prevented and the resulting product retain the fluffy fibrous forms of the fibrous linters. After the caustic soda is neutralized the product consists of the cellulose-ethylene oxide compound, hydroxy-ethyl cellulosel ether. It may be washed with water to neutrality and then dried. The resulting product still retains its fibrous, fluffy condition and may be kept indefinitely. It may be dissolved in dilute caustic soda solution at any time and utilized as described Yin the' following paragraph (B).`

(B) The fluffy alkaline cellulose-ethylene oxide product is stirred in to water so that the cellulose concentration is from about 51/2% to 8% (based on the original weight of air dry cellulose used). There should be enough caustic soda present in the product so that the diluted solution contains at least 2% and preferably 21/2% .of caustic soda. If the concentration is below this enough caustic soda is added to bring it up to the desired amount. The cellulose compound forms a clear viscous solution in the dilute caustic sod This solution may be filtered to remove any dissolved impurities. If the solution is too viscous for the next operations it may be aged to reduce this viscosity without decreasing the cellulose concentration. This solution is then passed through suitable dies or formed on suitable shapes to make lms, filaments and other products. It then is passed directly into an acid coagulating bath such as 5% sulphuric acid which may contain 15% of sodium sulphate. The caustic soda is neutralized forming a film, filament or other article 'of water insoluble cellulose-ethylene oxide or cellulose hydroxy-ethyl ether gel. The gel is washed with water and dried. Other operations may be carried out on the formed gel before drying depending upon the use to which it is to be put. Fillers and pigments may be incorporated in the viscous alkaline solution if desirable.

EXAMPLE 1I Making compounds containing 7% of ethylene oxide using refrigeration (A) Sheets of chemical wood pulp high in alpha cellulose are used as the raw material in this case. Sufficient wood pulp is taken so that it contains 100 parts by weight of dry cellulose. The sheets of wood pulp are mercerized in the 30% caustic soda solution in the same manner as given in Example I. After squeezing the excess caustic soda from the wood pulp it is shredded into a fluffy mass. As in Example I, the alkali cellulose is put into a tightly closed reaction chamber in which it is stirredvigorously, while about 7 parts by weight of gaseous ethylene oxide are admitted to the chamber. After the ethylene oxide has reacted completely with the alkali cellulose the reaction mass is removed from the reaction chamber. This product may be dissolved in a caustic soda. solution of at least about 6% strength. It contains some undissolved cellulosic products which may not be objectionable for certain purposes, as in certain coating operations. The undissolved cellulosic materials may be made practically entirely soluble by the refrigeratingf operation to be described. Enough water is added to the reaction mass to bring the caustic sodasolution strength down to about 4.75%. The entire mass is now refrigerated until it freezes. usually at a temperature of about 20 C. The frozen mass is removed from the refrigerating chamber and a1- lowed to melt. Enough caustic soda is added prior to melting to produce a flnal 6% caustic 110 soda solution. The solution which results is clear and viscous.

(B) The concentration of cellulose ether in the final solution produced in (A) is not high enough to make it suitable for the production of films, filaments, and the like. To bring the ether concentration to the desired amount for 4the production of films and filaments, usually about 8%, the procedure is modified somewhat. After the etherincatim iscompted, .about onethim 1 of the ether reaction mass is removed and neutralized by adding a. 5% to 10% solution of hydrochloric or sulfuric acid. The neutralized ether is washed free of salts after which it is returned to the two-thirds portion which was not treated with acid. The entire mass is then diluted with water to bring the caustic soda concentration to 4.75% as in (A). By this procedure the`concentration of ether with respect to the necessary to give the desired nal concentration. The entire mass is now refrigerated and melted as described in (A). The resulting clear viscous solution which results may be manipulated as EXAMPLE III Making compounds containing 12% of ethylene oxide suitable ,for films of highest transparency 14's The procedures as given in Example II are followed except that l2 parts by weight of ethylene oxide are used and a high grade pulp is used such as is suitable for the viscose type of articaustic soda solution is increased to the vamount ma ficial silk known as rayon. After refrigeration the product may be dissolved in a weaker solution of caustic soda compared to the 6% caustic soda solution needed to dissolve the compound containing '1% of ethylene oxide given in Example II. A 4% to 5% caustic soda solution is sufficient.

' EXAMPLE IV Making water soluble compounds from wood pul ,and ethylene oxide The alkali cellulose is made as described in Example II. After the excess caustic soda solution is removed from the wood pulp it is allowed to stand in limited contact with the air for a period of about 24 hours or more. This may be accomplished by putting the alkali cellulose in a container which does not have a tight fitting cover, thereby also preventing excessive carbonation of the alkali. The alkali cellulose is then etheriiied with a large amount of ethyleneloxide. to 95% or more ethylene oxide, depending on various factors, is used, this amount being based nv the amount of cellulose used in the form of pulp. The resulting compound may now be dissolved in water. The alkali may be vneutralized with a mineral acid, such as hydrochloric or sulphuric. Coagulation does not take place. The salts of hydrochloric and sulphuric acid which are formed when the caustic soda is neutralized by these acids may be removed'from the compound by dialysis. -If acetic acid has been used to neutralize the caustic soda then the resulting sodium acetate may be removed by treating the entire mass with alcohol. Since the sodium acetate is soluble in alcohol this effectsl a separation from the cellulose compound.

EXAMPLE V Etherifcanm with ethylene oxide dissolved in solvents I The alkali cellulose is prepared as described in either Examples I or II. A 20% solution of ethylene oxide in benzol is made. The wet a1- kali cellulose is submerged in the benzol solution of ethylene oxide for 48 hours at a temperature of about 4 C. after which the excess of benzol and oxide is removed as by centrifuging or distillation. The resulting compound of cellulose and ethylene oxide is soluble in weak caustic soda solutions and is treated as described in Example I to form other products therefrom. The etherication of `alkali cellulose apparently takes place much more slowly in the liquid phase than in the vapor phase.

vEXAMPLE: VI v Etherication with liquid ethyzenoxide The alkali cellulose is madeas described in Example I. The wet alkali cellulose after squeezing out the excess of caustic soda is submerged in liquid ethylene oxide. After being submerged or wetted with the liquid for a period of 20 hours at 4 C..it is removed and the excess ethylene oxide driven oil' by warming. The resulting product is soluble in dilute caustic soda solutions The alkali cellulose is made as is described in Example I. About 100 parts by weight of fluffy iibrous alkali celluloseis introduced into the reaction chamber. The reaction chamber is evacuated after which lthe requisite amount of -propylene oxide Vapor is introduced intol it.

About l12.4 parts by weight of propylene oxide are used. Since the propylene oxide boils at 35 C. it is desirable to keep the reaction chamber at that temperature or slightly higher if evacuation is not used. After the propylene oxide has been completely absorbed by the alkali cellulose the resulting product resembles that after etherication described in Example l1. The procedure for isolating this compound and using it in the various forms follows the procedure outlined in Example II. Compounds containing varying amounts of propylene oxide may be made according to the procedures outlined in Examples I, III, IV, V and VI, having ldue regard to the .differences in the two compounds.

EXAMPLE VIII v Making compounds of starch and ethylene oxide About 100 parts by weight of ordinary corny 'of ethylene oxide gives a water soluble, translucent compound that is doughy but sticky in consistency. The excess caustic soda may be dialyzed from the water soluble starch compound. Acetic acid may be used to neutralize the excess caustic soda and the resulting sodium acetate separated from the carbohydrate compound by ethyl alcohol.

EXAMPLE IX Making-cellulose hydroxy-ethyl ether using ethylene chlorhydrin Method A.The wet alkali cellulose, made as described in Example I, is introduced into a tightly closed reaction chamber having a stirrer and a false perforated bottom. Into the chamber underneath the false bottom, equal parts'of a 20% caustic soda solution and ethylene chlorhydrin of specific gravity V1.15 are introduced. Enough of the two solutions are used to generate about 20 parts by weight of ethylene oxide. The bottom of the reactiontank is then warmed so vas to generate the ethylene oxide more quickly.

After ,the ethylene oxide is completely evolved and has reacted with the alkali cellulose the resulting compound of cellulose and ethylene oxide is removed from the reaction chamber. This compound is similar to 'that obtained in Example I and the balance of the procedure is the same as that given in Example I.'

Method B.In this method the ethylene oxide is generated by the caustic soda used to mercerize the cellulose, enough caustic soda solution remaining in the alkali cellulose so that it will react with the Iethylene chlorhydrin -to form ethylenel oxide. Two pounds of wood pulp are Wetwith 12 parts by weight' of 20% caustic soda solution at about 22 C. for a few minutes and only the excess is drained ol to leave a soaked alkali cellulose weighing '7 to 9 times the air dry weight of the cellulose.v The alkali cellulose is then introduced into a container which may be made tight and refrigerated at about- 0 C. for

about 30 minutes. Six parts by weight of ethylene chlorhydrin of 1.2 specific gravity are added to the alkali cellalose containing the excess caustic soda solution. The reaction mass is stirred continuously at about 6 C. for one or two hours `and then allowed to come to room temperature and stirredv at this temperature for 24 to 48 hours. Heating to about 30 C. hastens the reaction. The resulting compound is soluble in vdilute caustic soda solution.

Method C.-The soda cellulose is made as in Example I except that a 40% caustic soda solution is used. After squeezing out the excess caustic soda solution the mixture is shredded into a wet fluffy brous mass. 100 parts by weight of cellulose are converted into wet uffy soda cellulose and treated with about 18 parts by weight of anhydrous or nearly anhydrous ethylene chlorhydrin. This amount oi chlorhydrin is equivalent to about 9 parts by weight of ethylene oxide. The mixture is stirred vigorously and preferably i`n a closed container. The temperature may be at room temperature or lower. The reaction is complete within an hour or two. The resulting reaction product may then be diluted with water to `.bring the caustic soda concentration to about 4.75% NaOH.- It may then be frozen as described in Example II. Instead of bringing the caustic soda concentration of the reaction mass to 4.75% it may first be diluted Wit-h Water to bring the caustic soda concentration to about.6% to 10% after which it is neutralized with an acid. This precipitates the ether, which is washed with water after which it is again wet with 4.75% NaOH and preferably to a concentration of 8.5% ether so that it may be used for the manufacture of films and filaments. The refrigerating operation then proceeds as in Example II.

EXAMPLE X Making cellulose dihydrozy propyl ether The alkali cellulose is made as described in Method C of Example IX. To 100 parts by weight of the cellulose in the form of wet, shredded uffy alkali cellulose about 22.5 parts by weight of anhydrous or nearly anhydrous glycerol monochlorhydrin are added and the etherication carried out as described with the ethylvene chlorhydrin in Method C of Example IX.

EXAMPLE XI Hydroy-ethyl-cellulose ether benzoate 100 parts by weight of alpha cellulose chemical wood pulp containing 8.5% moistureis steeped in a 30% caustic soda solution at 18 C. for 45,min-

utes. The soda cellulose is squeezed to about 350 parts by weight, shredded, and aged 21 hours at .-l 19 C. The alkali cellulose is churned in a closed fcontainer 21/2 hours with 12 parts by weight of ethylene oxide. The ether is further agitated with 15 parts by weight of benzoylchloride for 30 minutes at vroom temperature in the presence of an excess of benzol. The resulting alkali-etherbenzoate is centrifuged to remove the benzol, dissolved in 4.75% caustic soda, frozen and thawed as in Examples II or III. A 7.5% solution of the resulting compound is made up in 7.5% solution of caustic soda for use in making films, filaments and other products. The process may be reversed, that is, the alkali cellulose may be first benzoylated and then etheried with the ethylene oxide with no appreciable differences in the final product.

The claims of the present application differ from those of the companion applications on the same disclosure in referring particularly to the process of freezing herein described and the product obtained thereby.

This application is a continuation in part of applicants earlier application, Serial No. 345,214, filed March 7, 1929, and which has since become abandoned. Certain subject matter not claimed in the present application is claimed in my coending applications Serial Nos. 475,249 and 475,250, filed August 14, 1930, and in Serial Nos. 477,752 and 477,753, filed August 25, 1930, as divisions of Serial'No. 475,249, led August 14, 1930, said divisional application 477,752 having issued June 14. 1932 as Patent No. 1,863,208.

I claim:

1. A composition of matter comprising a mixture of caustic soda solution and a compound of cellulose comprising an hydroxy-alphyl ether of cellulose and the other cellulose products formed -during the etherification of at least two units of cellulose as alkali cellulose with one alphyl radical, said mixture being at least partially frozen to form a solution of the cellulose ether in the caustic alkali.

2. A composition of matter comprising a mixture of caustic alkali solution and a compound of cellulose comprising an hydroxy-alphyl ether of cellulose from ethyl to, propyl inclusive and the other cellulose products formed during the etherication of at least two units of cellulose as alkali cellulose with one alphyl radical, said mixture being at least partially frozen to form a solution of the cellulose ether in the caustic alkali.

3. A composition of matter comprising a solid` frozen mixture of caustic alkali solution and a. compound of cellulose comprising an hydroxyethyl ether of cellulose, and the other cellulose products formed by the reaction of one molecule of ethylene oxide with two units of cellulose as alkali cellulose.

4. A composition of matter comprising a mixture of caustic alkali solution of about 2% .to 10% caustic alkali and hydroxy ethyl ether of cellulose containing on the average not more than 20% of combined ethylene oxide based on the weight of the cellulose combined with said oxide, said mixture having been refrigerated until at least a portion of said caustic alkali solution is frozen to form a solution of the cellu j' lose ether in the caustic alkali.

5. A composition of matter comprising a mix-- ture of caustic alkali solution of about 2% to- 10% caustic alkali and hydroxy propyl ether of cellulose containing on the average no more than 22.4% of 'combined propylene oxide based on the weight of cellulose combined with said oxide, said mixture having been refrigerated until at least a. portion of said caustic alkali solution is frozen to form a solution of the cellulose j. 1

ether in the caustic alkali.

6. A composition of matter comprising a mixf ture of caustic soda solution and a cellulose hydroxy-alphyl ether from ethyl to propyl inclusive containing at least two units of cellulose combined with one alphyl radical, said mixture potash solutions,

being at least partially frozen to form a solution of the cellulose ether in the caustic alkali.

7. A composition ofmatter comprising a solid frozen mixture of caustic soda solution and a cellulose hydroxy-ethyl ether containing less than one ethyl radical for each two cellulose units.

8. A composition of matter comprising a mixture of caustic alkali solution and cellulose hydroxy ethyl ether which is insoluble in water -and which is at most of limited solubility in caustic said ether containing on the average not more than 20% of combined-ethylene oxide based on the weight of cellulose combined with said oxide, said mixture having been refrigerated until at least a portion of said caustic alkali solution is frozen to form a solution of the cellulose ether in the caustic alkali.

9. A composition of matter comprising a mixture of caustic alkali solution and cellulose hydroxy propyl ether of cellulose which is insoluble in water and which Ais at most of limited l solubility in caustic potash solutions, said ether containing on the average no more than 22.4% of combined propylene oxide based on the weight oi cellulose combined with said oxide, said mixture having been refrigerated until at least a.

portion of ,said caustic alkali solution is frozen to form a solution of the cellulose ether in the caustic alkali.

l0. A composition of matter comprising a solid frozen mass oi caustic alkali solution and a cellulose hydroxy. ethyl' ether containing less than 20% of ethylene oxide combined with the l cellulose based on the weight4 of the cellulose.

1l. A composition ci matter comprising ay mixture of caustic alkali solution of about 2% to 10% caustic alkali and hydroxy alphyl ether of cellulose containing on the average no more combined olene oxide than the molecular equivalent of 20% of combined ethylene oxide based 'on the weight of cellulose combined with said oxide, said .mixture having' been refrigerated until at least a portion of said caustic alkali solution is frozen to form a solution of the cellulose ether in the caustic alkali.

12. A composition of matter comprising a liquid solution containing ice, caustic soda, and a solution of cellulose hydroxy alphyl ether, from ethyl to propyl, said mixture resulting when refrigerating said caustic alkali solution and ether until ice crystals form, which ether is at most of limited solubility in caustic potash solutions, said ether containing on the average no more combined oleiine oxide than the molecular equivalent of 20% of combined ethylene oxide based on the weight of cellulose combined with said oxide.

13. The method or" rendering a reaction product of alkali'cellulose and an etherifying cherni'- cal producing an hydroxy-ethyl ether of. cellulose more soluble in dilute caustic alkali solution, said ether containing on the average not more than 20% of combined ethylene oxide based on the weight of cellulose combined with said oxide, and said reaction product being originallyincomp'letely soluble in dilute caustic alkali solutions at above 0 C., which comprises mixing the cellulose recontaining on the average of alkali cellulose and an etherifying chemical producing an hydroxy propyl ether of cellulose not more than 22.4% of combined propylene oxide based on the Weight of cellulose combined with said propylen'e oxide, said propyl ether being originally incompletely soluble in dilute caustic alkali solutions of above 0 C., which method comprises mixing the said cellulose reaction compound with a solution of about 2% to 10% caustic'alkali, and refrigerating said mixture until at least a portion of said l caustic alkali solution freezes.

15. The method of renderinga reaction product ofalkali cellulose and ethylene oxide containing not more than one ethyl radical to two cellulose units moresoluble in dilute caustic soda solution, said product being originally incompletely soluble in said dilute caustic soda solution at above 0 cellulose-ethylene oxide compound with a solution of about 4% to 6% caustic` soda, and-refrig- 4erating said .mixture until at least a portion of said caustic soda solution freezes. l

16. The step in the method of rendering more soluble in a dilute caustic soda solution a reaction product of cellulose and ethylene oxide containing on the average not more than 20% of combined ethylene oxide based on the weight of the cellulose combined with said oxide and which is originally incompletely soluble in said solution C., which comprises mixing the' at above 0 C., which comprises refrigerating at about 20 C. a mixture vof the cellulose, ethylene oxide reaction product and a caustic 'soda solution which starts freezing at about -0.3 C. to 10 C. until a solid mass of crystals forms.

17. The method of increasing the solubility in dilute caustic soda solution of the reaction products produced by the etherication of alkali cellulose to produce hydroxy-propyl ethers of cellulose, said products containing onthe average not more than 22.4% of combined propylene oxide basedon the weight of cellulose combined withv said oxide, being insoluble in Water, and being at most only partially soluble in caustic potash solutions, said products being originally incompletely soluble in a dilute caustic soda solution at above 0 C., which comprises mixing the reaction products with la solution of caustic soda which starts freezing at about -0.3 to 10 C., refrigerating said mixture until at least a portion of said caustic soda solution freezes, and melting said solidiiied mixture.

18. The method of making hydroxyl-alphyl ethers of cellulose containing less than one alphyl radical combined. with two units of cellulose, which comprises mercerizing cellulosic material to form alkali cellulose, etherifying the alkali cellulose with the required amount of etherifying agent, adding water to thereaction mass to dilute the caustic alkali to about 2% to 10%, and refrigerating the product formed until at least a portion of said alkalisolution freezes.

19. The method of producing from cellulosic raw material which has not been degraded apentirely soluble in a 10% to 15% caustic soda so` lution, said products being substantially entirely hydroxy-ethyl ethers of cellulose containing less than one ethyl yradical vcombined vwith two units of cellulose, which comprises soaking said cellulosic raw material in caustic soda solution of suilicient strength to form alkali cellulose, expressing'the excess solution. reacting vapors oi la@ 'preciably cellulose products which are practically ethylene oxide with the alkali cellulose so formed l5@ in the proportions of one molecule of ethylene oxide to about 2 to 4 units of cellulose in said raw material, adding Water to the product until the caustic soda solution is reduced to about 4% to 6%, and refrigerating the product until a solid mass of crystals forms.

20. The method of manufacturing cellulose lproducts which are practically entirely soluble in a 5% to 15%'caustic sodalsolution, said products being substantially entirely hydroxy-ethyl ethers of cellulose containing less than one ethyl cient hydroxy-ethyl ether of cellulose to bringthe. final ether concentration to '7% to 9%, and refrigerating the product at a temperature below about -20 C. until a solid mass of crystals forms.

2l. The method of producing a solid, transparent hydroxy-ethyl ether of cellulose containing not more than one hydroxy-ethyl/radical to two to four units of cellulose, which comprises subjecting wet alkali cellulose to the required amount of etherifying agent, freezing to a solid mass a mixture of the resulting reaction product and a solution of caustic soda which starts freezing at 0.3 C. to 10 C., forming a dilute caustic soda solution of the frozen product, and subjecting said solution to a coagulating bath.

22. The process of making a hydroxy-ethyl ether of cellulose having properties suitable for the making of strong and flexible filaments and lms, said laments and lms after drying being characterized by being at most partially soluble in caustic potash solutions, which comprises treating cellulose that has not been greatly degraded with caustic alkali to form alkali cellulose, reacting said alkali cellulose With ethylene oxide in the ratio of one molecule of said oxide to more than two units of cellulose in said alkali cellulose, rendering the resulting product of cellulose and oxide more completely soluble in dilute caustic soda by freezing solidly said product at below about 20 C. with a 4% to 6% caustic soda solution, and melting said mixture to form a dilute caustic soda solution of said product.

23. The step in the method for dissolving in caustic alkali solution an hydroxy-ethyl ether of cellulose containing on the average not more than 20% of combined ethylene oxide based on the Weight of cellulose combined with said oxide. which comprises refrigerating a mixture of said ether With'a dilute caustic alkali metal hydroxide until at least some of said caustic alkali solution freezes, and melting the frozen portion.

24. The step in the method for dissolving in caustic alkali an hydroxy propyl ether of cellulose containing on the average not more than 22.4% of combined propylene oxide based on the weight of cellulose "combined with said oxide, and which is deficient in substituted propyl radical to the extent that the ether is not completely soluble in dilute caustic alkali solution by introduction therein, which comprises refrigerating a mixture of said 'ether in dilute caustic alkali metal hydroxide solution until at least a portion of said hydroxide solution freezes, and melting the frozen product.

25. The method of dispersing normally insoluble hydroxy-alphyl ether of cellulose containing one molecule of olef'lne oxide to more than two units of cellulose in, a solution 'of caustic alkali metal hydroxide Icontaining normally dispersed hydroxy-alphyl ether of cellulose, which comprises refrigeratirig the mixture until the mass freezesjsolidly, and then heating to melt the frozen mass.

26.4' The method of dispersing in a caustic alkali metal hydroxide solution a normally insoluble hydroxy alphyl ether of cellulose containing on thel average an insuflicient quantity of alphyl radical for complete solubility and containing not more olefine oxide combined with the cellulose than the molecular equivalent of 20% of combined ethylene oxide based on the weight of the cellulose combined with said olefine oxide, which comprises subjecting the mixed material to refrigeration until the mass is at least partially frozen and then reheating the mass to melt it.

27. The method of treating a mixture of solvent caustic soda solution of 2% to 10% concentration and an incompletely soluble hydroxyethyl ether of cellulose containing on the average no more than 20% combined ethylene oxide based on the weight of cellulose combined with said oxide in order to increase the solubility of the said ether in said solvent, which comprises cooling the mixture to a point where at least a portion of said caustic soda solution freezes, and thereafter melting the frozen portion, whereby increased solubility of the ether in the original solvent results.

28. The method of treating a. mixture of solvent caustic soda solution of 2% to 10% concentration and an incompletely soluble hydroxypropyl ether of cellulose containing on the average less than 22.4% of propylene oxide based on the weight of cellulose combined with said oxide, in order to increase the solubility of the said ether in said solvent, which comprises cooling the mixture to a point where at least a portion 'of said f to 10% caustic alkali solution until at least al portion of said caustic soda solution freezes, and melting the frozen portion. i

30. A composition of matter comprising a solid cellulose hydroxy-ethyl ether containing less than 20% of combined ethylene oxide based on the weight of the cellulose combined with said oxide and derived from a previously frozen caustic al-. kali solution of the same, said ether being characterized by a decrease in solubility in caustic alkali upon transition from the said state in solution to the said solid state.

3l. The method of preventing the gelling of an hydroxy ethyl ether of cellulose containing on the average no more than 20% of combined ethylene oxide based on the weight of cellulose combined with said oxide upon the melting of apreviously frozen caustic alkali solution of the same, wherein said ether gels upon thawing, which com prises increasing the caustic alkali concentration of the solution during the thawing operation.

32. The method of increasing the solubility'in a solvent caustic alkali solution of an hydroxy ethyl ether of cellulose containing on the average no more than of combined ethylene oxide based on the weight of the cellulose combined with said oxide, which comprises freezing a mixture of said ether and said solvent solution until at least a portion of the caustic alkali solution' freezes, and simultaneously adding solid caustic comprises increasing the caustic soda concentration of the solution above 6% during the thawing operation.

34. The method for preventing the gelling of an hydroxy'ethyl ether of cellulose containing on the average not more than 20% of combined ethylene oxide based on the weight of the cellulose combined with said oxide upon the melting of a previously frozen caustic soda solution of the same, the ether concentration being from 7% to 9% wherein said ether gels upon thawing, the caustic soda solution being from 4% to 6%, which comprises increasing the caustic soda concentration of the solution above 6% during the thawing operation.

35. 'The method of preventing the gelling of an hydroxy alphyl ether of cellulose containing on the average no more combined olene oxide than the molecular equivalent of 20% of combined ethylene oxide based on the weight of cellulose combined with said oxide, upon the melting of a previously frozen caustic alkali solution of the same, wherein said ether gels upon thawing, which comprises increasing the caustic alkali concentration of the solution during the thawing operation.

ARLIE W. SCHORGER. 

